Fuel cell, fluid distribution device for fuel cell, and vehicle provided with fuel cell

ABSTRACT

A fuel cell contains two or more fluid-supplying internal manifolds and fluid-discharging internal manifolds for each fluid. External manifolds include fluid-supplying external manifolds, which connect to the fluid-supplying internal manifolds, and fluid-discharging external manifolds, which connect to the fluid-discharging internal manifolds, for each fluid. The respective fluid-supplying and fluid-discharging external manifolds are positioned approximately in parallel with each other, extending in the width direction of a cell laminate body.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National stage application of InternationalApplication No. PCT/JP2014/056051, filed Mar. 7, 2014, which claimspriority to Japanese Application No. 2013-046984 filed in Japan on Mar.8, 2013, the contents of each of which is hereby incorporated herein byreference.

BACKGROUND

1. Field of the Invention

The present invention relates to a fuel cell, a fluid distributiondevice for a fuel cell, and a vehicle with a fuel cell. Morespecifically, the present invention relates to a compact, high-outputfuel cell, a fluid distribution device thereof, and a vehicle with afuel cell.

2. Background Information

A fuel cell is a type of power generating device for extractingelectricity by electrochemically oxidizing fuels such as hydrogen andmethanol, which has been drawing attention as a clean energy source inrecent years. Fuel cells are classified into phosphoric acid types,molten carbonate types, solid oxide types, polymer electrolyte types,etc., according to the type of electrolyte used.

Of these, a polymer electrolyte fuel cell (PEFC) comprises a membraneelectrode assembly (MEA) in which electrodes are disposed on bothsurfaces of an electrolyte membrane. Power is then generated bysupplying hydrogen (fuel gas) on one surface and oxygen (oxidation gas)on the other surface of the membrane electrode assembly. Since avolumetric output density equivalent to an internal combustion enginecan be obtained with such a PEFC, research is being advanced on thepractical applications thereof as a power source for electric vehicles,etc. (refer to, for example, Patent Documents 1 and 2).

Various types of packaging methods for the membrane electrode assemblyhave been proposed, such as the stacked type, the pleated type, and thehollow fiber type. Of these, stacked fuel cells, which are configured bystacking sheet-shaped membrane electrode assemblies with sheet-shapedseparators in between, are being widely used.

The output of a fuel cell is proportional to the membrane area and isnot proportional to the fuel cell volume. Accordingly, reducing the cellpitch is effective at achieving miniaturization and high output in astacked fuel cell. However, if only the cell pitch is reduced, pressureloss becomes excessive when fluids such as air, hydrogen, and coolingwater pass through the inner surface of the cells. The result ofexcessive pressure loss is contrary to the demand for a reduction inauxiliary power and, thus, is not preferable.

Accordingly, the present inventors have proposed a fuel cell comprisinga low-aspect structure in which the length in the width directionperpendicular to the flow channel direction is longer than the length inthe flow channel direction of an approximately rectangular fuels cell(refer to WO 2011/059087).

Fluid that is supplied to a fuel cell is supplied via various fluidmachinery, such as a compressor, an ejector, a floor, and a pump, aswell as via additional piping. For example, in a fuel cell used forautomobiles, each fluid is supplied via pipes having a diameter of about50 mm. Accordingly, when the length in the width direction issignificantly wider, when compared to the sizes (diameters) of suchpipes, evenly supplying the fluid across the entire width directionbecomes difficult. Therefore, a fuel cell having a low-aspect structurerequires a fluid distribution mechanism for expanding the size of fluidflow from the size (diameter) of the pipes to the size of the low-aspectstructure fuel cell in the width direction. However, a conventionalfluid distribution mechanism configured by combining a plurality ofpipes is large and bulky; as a result, there is the problem thatminiaturization of the fuel cell as a whole is inhibited. See also,Japanese Laid-Open Patent Application No. 2005-190946 JP and JapaneseLaid-Open Patent Application No. 2007-287659 JP.

SUMMARY

Therefore, the object of the present invention is to provide a fuel cellhaving a low-aspect structure that is long in the width direction of anelectrode layer, in which the respective types of necessary fluid forthe fuel cell are supplied or discharged evenly in the width directionand the laminate layer direction; and a fluid distribution device thatis suitable for use in such a fuel cell and a vehicle with a fuel cell.

Upon carrying out intensive research in order to achieve the objectivedescribed above, the present inventors found that the problem can besolved by providing a fluid distribution mechanism comprising aninternal manifold disposed inside of a cell laminate body that has aspecific structure and an external manifold disposed outside of the celllaminate body, producing the present invention.

That is, to achieve the objective described above, the fuel cellaccording to the present invention comprises a cell laminate body, whichis formed by laminating a substantially rectangular separator and amembrane electrode assembly equipped with substantially rectangularanode and cathode electrode layers located on opposite surfaces of asubstantially rectangular electrolyte membrane; the fuel cell alsocomprises an anode flow channel, a cathode flow channel, and a coolingfluid channel inside, as well as external manifolds that are outside ofthe cell laminate body for supplying or discharging the respectivefluids with respect to the cell laminate body. In the cell laminatebody, at least the anode flow channel and the cathode flow channel areconfigured from a plurality of linear ribs; the aspect ratio R (L/W),which is the ratio of the length (L) of the electrode layer along theflow channel direction and the width (W) of the electrode layer in thewidth direction that is perpendicular to the flow channel direction, isless than 1; two or more flow channel openings are disposed on each ofthe two ends of the respective flow channels; and the flow channelopenings are laminated so as to configure two or more fluid-supplyinginternal manifolds and two or more fluid-discharging internal manifoldsfor each of the anode gas and the cathode gas.

The external manifolds include fluid-supplying external manifolds, whichconnect to the fluid-supplying internal manifolds via a supply-sidecommunicating portion, and fluid-discharging external manifolds, whichconnect to the fluid-discharging internal manifolds via a discharge-sidecommunicating portion. The respective fluid-supplying andfluid-discharging external manifolds are positioned approximatelyparallel to each other, extending in the width direction of the celllaminate body. The supply-side communicating portion and thedischarge-side communicating portion comprise a first auxiliarymanifold, which is connected to the internal manifold, and a secondauxiliary manifold, which is connected to the external manifold andcomprises a center line that intersects with the center line of theexternal manifold and the center line of the first auxiliary manifold,with respect to at least one fluid of the anode gas or the cathode gas.

In this embodiment, an inlet that opens at the end of thefluid-supplying external manifold and an outlet that opens at the end ofthe fluid-discharging external manifold are positioned on one end sideof the cell laminate body in the laminate layer direction and are openedin the same direction, with respect to at least one fluid of the anodegas or the cathode gas.

The fluid distribution device according to the present invention, whichachieves the object described above, is used in the fuel cell describedabove for distributing at least two fluids among the anode, cathode, andcooling fluids; the fluid-supplying external manifolds and thefluid-discharging external manifolds are formed with respect to each ofthe first and second fluids and comprise a block body that configures anend plate.

Here, if the surface on the side of the block body to which the celllaminate body is disposed were to be one surface, the external manifoldfor the first fluid that flows on the side closer to the one surface andthe external manifold for the second fluid that flows on the sidefarther from the one surface are disposed partially overlapping, whenviewed from the one surface side of the block body. Additionally, theexternal manifold for the second fluid includes an extension portionthat does not overlap with the external manifold for the first fluid,when viewed from the one surface side of the block body. Then, acommunicating portion for the first fluid is formed by forming a firsthole portion that communicates only with the external manifold for thefirst fluid from the one surface side, and a communicating portion forthe second fluid is formed by forming a second hole portion thatcommunicates only with the external manifold for the second fluid in theextension portion from the one surface side.

The vehicle according to the present invention that achieves the aboveobjective comprises the fuel cell described above.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of thisoriginal disclosure.

FIG. 1 is a perspective view illustrating the fuel cell according to afirst embodiment.

FIG. 2 is a perspective view illustrating the cell laminate body.

FIGS. 3A-3C illustrates a unit cell that configures the cell laminatebody; FIG. 3A is a plan view of the separator, FIG. 3B is a plan view ofthe membrane electrode assembly when a sealing material is attached, andFIG. 3C is a view of the separators disposed on both sides of themembrane electrode assembly.

FIG. 4 is an exploded view of the membrane electrode assembly.

FIG. 5A is a plan view illustrating the membrane electrode assembly,FIG. 5B is a plan view illustrating the membrane electrode assembly whena sealing material is attached, and FIG. 5C is an enlarged plan viewillustrating the principle parts of a widened portion formed between theflow channel opening and the catalyst layer for the internal manifold.

FIG. 6A is a perspective view illustrating a separator to which a gasflow channel is formed, and FIG. 6B is an enlarged perspective viewillustrating the gas flow channel.

FIG. 7A is a view illustrating a separator with a high aspect ratio,FIG. 7B is a view illustrating a separator with a low aspect ratio, andFIG. 7C is a view illustrating a separator with a low aspect ratio and alow flow channel height.

FIG. 8 is a plan view illustrating an end plate incorporating a fluiddistribution device.

FIG. 9A is a perspective view illustrating a cross section of theprinciple part of the end plate that incorporates a fluid distributiondevice, and FIG. 9B is a cross-sectional view illustrating an end plateto which is provided an external manifold.

FIG. 10 is an explanatory view showing the first and second auxiliarymanifolds disposed on a communicating portion for connecting an externalmanifold and an internal manifold, using the fluid supply side as anexample.

FIGS. 11A-11C are cross-sectional views illustrating the states in whichthe first and the second auxiliary manifolds in the supply-sidecommunicating portion, as well as the first and the second auxiliarymanifolds in the discharge-side communicating portion, are formed foreach fluid in the block body configuring the end plate.

FIGS. 12A and 12B are views illustrating an example of a vehicleequipped with a fuel cell.

FIG. 13A is a view schematically illustrating an example of a layout ofthe cell laminate body and the external manifold.

FIG. 13B is a view schematically illustrating an example of a layout ofthe cell laminate body and the external manifold.

FIG. 13C is a view schematically illustrating an example of a layout ofthe cell laminate body and the external manifold.

FIGS. 14A and 14B are a perspective view and a plan view illustratingthe fuel cell according to a second embodiment.

FIG. 15A is a perspective view illustrating a cross section of theprinciple part of the lower side end plate that incorporates a fluiddistribution device according to the second embodiment, and FIG. 15B isa cross-sectional view illustrating the lower side end plate to which isprovided an external manifold.

FIGS. 16A and 16B are cross-sectional views illustrating the states inwhich the first and the second auxiliary manifolds in the supply-sidecommunicating portion, as well as the first and the second auxiliarymanifolds in the discharge-side communicating portion, are formed foreach fluid in the block body configuring the lower side end plate.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Preferred embodiments of the present invention will be explained below,with reference to the drawings; however, the technical scope of thepresent invention shall be determined based on the recitation of theclaims and is not limited to the following embodiments. In theexplanations of the drawings, the same elements have been given the samereference codes, and the overlapping explanations have been omitted. Thedimensional ratios in the drawings have been exaggerated for theconvenience of explanation, and they are different from the actualratios.

First Embodiment

The fuel cell 1 of the first embodiment is a stacked fuel cell,comprising a cell laminate body 20, in which a plurality of unit cells 4are laminated, which is one unit of a fuel cell in which a set ofsheet-like separators 2 and sheet-like membrane electrode assemblies 3are laminated, as illustrated in FIG. 1-FIG. 3C. The number oflaminations of the unit cell 4 is not particularly limited; both thosewith a single unit cell 4 and those laminating a plurality of unit cells4 are included in the fuel cell according to the present invention.Collector plates (not shown) are positioned at both ends of the celllaminate body 20 in the laminate layer direction of the unit cells. Thecollector plate comprises an output terminal to remove the electromotiveforce that is generated in the cell laminate body 20. Both ends of thecell laminate body 20 are sandwiched by a pair of end plates 31, 32,which are disposed on the outer side of the collector plate. A fuel cellstack is thereby configured. A fluid distribution device 100 isconnected to, preferably, the outer lower part of the cell laminate body20.

External manifolds 42, 43, 44 for supplying or discharging the necessaryvarious fluids to the fuel cell 1 with respect to the cell laminate body20 are disposed on the fluid distribution device 100, as illustrated inFIG. 1 and FIG. 8-FIG. 11C. In the first embodiment, the externalmanifolds 42, 43, 44 for all of the fluids are inside of one end plate32, from among the end plates 31, 32. The external manifolds 42, 43, 44may be collectively referred to as the “external manifolds 41.” The fuelcell 1 of the first embodiment will be described in detail below.

Membrane Electrode Assembly

The membrane electrode assembly 3 is a joined body comprising thefollowing five layers, in order from the back to the front: gasdiffusion layer 5 a—catalyst layer 6 a—electrode layer 7—catalyst layer6 b—gas diffusion layer 5 b, as illustrated in FIG. 4. The membraneelectrode assembly 3 generally has a substantially rectangular shape inplain view. The membrane electrode assembly 3 forms a fuel cell by beingcombined with a similarly substantially rectangular separator 2 tosupply or discharge oxygen (oxidation gas) and hydrogen (fuel gas).

In the membrane electrode assembly 3, the surface comprising a catalystlayer 6 a on the hydrogen side is referred to as the anode, and thesurface comprising a catalyst layer 6 b on the oxygen side is referredto as the cathode. The membrane electrode assembly 3 may be referred toas the MEA (membrane electrode assembly), and the gas diffusion layer 5may be referred to as the GDL (gas diffusion layer).

Also, the three layers of the catalyst layer 6 a—the electrode layer7—the catalyst layer 6 b may be referred to as the CCM (catalyst coatedmembrane), and the two layers of the catalyst layer 6 (6 a, 6 b may becollectively referred to as 6)—the gas diffusion layer 5 (5 a, 5 b maybe collectively referred to as 5) may be referred to as the gasdiffusion electrode or the GDE (gas diffusion electrode). Additionally,the layer comprising the catalyst layer 6 and the gas diffusion layer 5may be referred to as the electrode layer, and the gas diffusionelectrode may simply be referred to as an electrode.

The membrane electrode assembly 3 and the separator 2 do not need to beperfect rectangles; they may be substantially rectangular as long as aflow channel length L and a flow channel width W described below can beidentified. That is, the corners of the rectangle may be chamfered orelliptical in shape.

Gas Diffusion Layer

The gas diffusion layers 5 a, 5 b supply the fuel gas and the oxidationgas supplied to the fuel cell to the catalyst layers 6 a, 6 b and sendand receive electrons between the catalyst layers 6 a, 6 b and theseparator 2. The gas diffusion layers 5 a, 5 b may further compriseother members (layers) on the surface, inside, or both thereof, within arange that does not inhibit the object of the present invention. Forexample, carbon particle layers comprising carbon particles may bedisposed on the catalyst layers 6 a, 6 b side of the gas diffusionlayers 5 a, 5 b.

The gas diffusion layers 5 a, 5 b are preferably porous bodiesconfigured from a conductive material and, more preferably, are a fibermaterial, including paper, nonwoven fabric, woven fabric, knitted fabricor a net. Examples of conductive materials include carbon materials andmetallic materials.

When the gas diffusion layer 5 is configured from fiber material, thehalf-value r of the average distance between fibers at the surface ispreferably equal to or less than 100 μm, is, more preferably, equal toor less than 50 μm, is even more preferably equal to or less than 20 μm,and is further preferably equal to or less than 15 μm; especiallypreferable is that the distance is equal to or less than 10 μm and, mostpreferably, is equal to or less than 5 μm. The half-value r of theaverage distance between the fibers defined here is half of the distanceof the average distance between fibers. That is, when the gas diffusionlayer comprises a plain weave fiber material made of vertical andhorizontal lines, the half-value refers to half of the distance betweentwo adjacent vertical lines or horizontal lines.

The gas diffusion layers 5 a, 5 b and the catalyst layers 6 a, 6 bdescribed above are separate layers in FIG. 4. However, the gasdiffusion layers and the catalyst layers may be integrated into a singlelayer.

Aspect Ratio

As described above, the fuel cell 1 comprises a cell laminate body 20formed by laminating a substantially rectangular separator 2 and amembrane electrode assembly 3 equipped with substantially rectangularanode and cathode electrode layers (catalyst layer 6 and gas diffusionlayer 5) located on opposite surfaces of a substantially rectangularelectrolyte membrane 7.

An anode flow channel, a cathode flow channel, and a cooling fluidchannel are inside of the cell laminate body 20. Of these three flowchannels, at least the anode flow channel and the cathode flow channelare configured from a plurality of linear ribs. Each flow channel isformed between two opposing sides and comprises a structure in whichfuel gas (anode gas), oxidation gas (cathode gas), cooling fluid, etc.are introduced from one side and are discharged from the other side.

In the fuel cell of the present embodiment, the aspect ratio R (L/W),which is the ratio of the length (L) of the electrode layer along theflow channel direction and the width (W) of the electrode layer in thewidth direction that is perpendicular to the flow channel direction, isless than 1.

Specifically, in an electrode layer of the substantially rectangularmembrane electrode assembly 3, when the direction in which the oxidationgas flows (the direction indicated by arrow M1) is considered to be theshort side and the direction that is perpendicular to the direction inwhich the oxidation gas flows (the direction indicated by arrow M2) isconsidered to be the long side, the aspect ratio R is defined by R=shortside/long side=L/W, as illustrated in FIG. 5B. The aspect ratio R of themembrane electrode assembly 3 is, strictly speaking, the ratio (L/W) ofthe length (L) with respect to the width (W) of the catalyst layers 6 a,6 b disposed on an active area in which power generation occurs. Since,in this embodiment, the membrane electrode assembly 3 is a conceptincluding the catalyst layers 6 a, 6 b, for convenience, the expression,aspect ratio R of the membrane electrode assembly 3, is used hereinbelow.

In the description above, the direction in which the oxidation gas flowswas considered to be the short side, the direction that is perpendicularto the direction in which the oxidation gas flows was considered to bethe long side, and the aspect ratio R of the membrane electrode assembly3 was defined as R=short side/long side=L/W. However, the direction inwhich the fuel gas flows on the anode side or the direction in which thecooling fluid flows in the cooling layer may be considered to be theshort side, and the direction that is perpendicular to the direction inwhich the fuel gas flows or the direction that is perpendicular to thedirection in which the cooling fluid flows in the cooling layer may beconsidered to be the long side when defining the aspect ratio R of themembrane electrode assembly 3.

The aspect ratio R of the membrane electrode assembly 3 is 0.01 or moreand less than 1. The lower limit of the aspect ratio is preferably 0.05or more, more preferably 0.1 or more, and even more preferably 0.2 ormore. On the other hand, the upper limit of the aspect ratio ispreferably less than 0.9, more preferably less than 0.8, even morepreferably less than 0.7, and most preferably less than 0.6. When theaspect ratio R is less than 0.01, the outer shape of the fuel cellbecomes too elongated, and there is the possibility that a problemoccurs when considering mounting the fuel cell to a vehicle.

In more detail, in the embodiment of a rectangular shape of the membraneelectrode assembly 3 in which the aspect ratio R is 0.01 or more andless than 1, the shape of the separator 2 is also configured in arectangular shape to match the membrane electrode assembly 3, asillustrated in FIG. 3. Then, for example, when a separator 2A has a highaspect ratio (R is equal to or greater than 1), the flow channel lengthalso becomes long, and the pressure loss increases, as illustrated inFIG. 7A. In contrast, when a separator 2B has a low aspect ratio (R is0.01 or more and less than 1), the flow channel length becomes short,and pressure loss decreases, as compared to the separator 2A, asillustrated in FIG. 7B. That is, even when the area is the same and theflow amount to the flow channel is the same as the separator 2A,pressure loss can be decreased by decreasing the aspect ratio R, as inthe case with the separator 2B. Consequently, even if the aspect ratio Ris set to be small and the height of the flow channel is lowered, as inFIG. 7C, a pressure loss similar to that in the separator 2A can bemaintained, and the height of the separator 2 can be lowered.

In addition, since the cross-sectional area of the flow channel will besmaller for the flow channel of the separator 2C than for the flowchannel of the separator 2B, the flow rate of the reaction gas will befaster in the flow channel of the separator 2C than in the flow channelfor the separator 2B. As a result, the generated water present in theflow channel can be blown away by the reaction gas, and flooding can besuppressed. In particular, while a configuration like the separator 2Cis preferably applied to the cathode side where generated water tends tobe retained, application to the anode side or application to the coolingfluid can also contribute to the miniaturization of the fuel cell.

In the fuel cell of the present embodiment, the direction in which thefuel gas flows is preferably parallel to the direction in which theoxidation gas flows. However, the direction in which the fuel gas flowscan also be perpendicular to the direction in which the oxidation gasflows (cross flow). When parallel, the direction in which the fuel gasflows and the direction in which the oxidation gas flows may be eitherthe same direction (co-flow) or opposite directions (counter flow); ofthese, a counter flow is preferred.

Additionally, in the present embodiment, the direction in which thecooling fluid flows is preferably parallel to the direction in which theoxidation gas flows; however, this may also be perpendicular (crossflow). When parallel, the direction in which the cooling fluid flows andthe direction in which the oxidation gas flows may be either the samedirection (co-flow) or opposite directions (counter flow); of these, aco-flow is preferred.

Flow Channel Opening

In the present embodiment, two or more flow channel openings aredisposed in each of the two ends of the respective flow channels (theanode flow channel, the cathode flow channel, and the cooling fluidchannel). By having two or more flow channel openings, even in the fuelcell of the present embodiment which is long in the width direction,supplying gas and cooling fluid evenly in the width direction is easy.

A plurality of fuel gas flow channel openings 9, cooling water flowchannel openings 10, and oxidation gas flow channel openings 11 aredisposed in the outer peripheral part of the two opposing sides (longsides) of the membrane electrode assembly 3, as illustrated in FIG. 5B.The cooling water flow channel opening 10 is sandwiched between the fuelgas flow channel opening 9 and the oxidation gas flow channel opening11. If necessary, the cooling water flow channel opening 10 may bedisposed on the short side of the outer peripheral part of the membraneelectrode assembly 3. Code “8” in FIG. 5C represents a widened portion,and code “12” represents a sealing material.

A plurality of fuel gas flow channel openings 9, cooling water flowchannel openings 10, and oxidation gas flow channel openings 11 are alsodisposed in the outer peripheral part of the two opposing sides (longsides) of the electrolyte membrane 7, as illustrated in FIG. 4 and FIG.5A. However, flow channel openings are not necessarily disposed in theelectrolyte membrane 7. For example, a carrier sheet made of resin, towhich includes flow channel openings, is disposed along the outer edgeof an electrolyte membrane having the same planar shape as the catalystlayer. Then, the outer edge of the electrolyte membrane and the inneredge of the carrier sheet are hermetically sealed. The same function asthe membrane electrode assembly 3 in FIG. 4 can thereby be expressed.

Additionally, sealing material 12 is disposed at the respective outerperipheral edges of the cathode side surface and the anode side surfaceof the membrane electrode assembly 3, as illustrated in FIG. 5B and FIG.5C. Specifically, the sealing material 12 is disposed at the outerperipheral edge of the cathode side surface of the electrolyte membrane7, so as to surround the entire outer periphery, as well as to surroundthe fuel gas flow channel openings 9 and the cooling water flow channelopenings 10. However, the sealing material 12 is not disposed around theoxidation gas flow channel openings 11. On the other hand, while adiagram has been omitted, sealing material 12 is disposed at the outerperipheral edge of the anode side surface of the electrolyte membrane 7,so as to surround the entire outer periphery, as well as to surround theoxidation gas flow channel openings 11 and the cooling water flowchannel openings 10. However, the sealing material 12 is not disposedaround the fuel gas flow channel openings 9.

The sealing material 12 comprises a switching function to select whichfluid (fuel gas, oxidation gas, or cooling fluid) to distribute to themembrane electrode assembly 3. For example, in FIG. 5B, the sealingmaterial 12 is opened in front of the oxidation gas flow channel opening11, so that the cathode side of the membrane electrode assembly 3 can beshown.

The sum AOx of the cross-sectional area of the oxidation gas flowchannel openings 11 is preferably equal to or greater than 5% and equalto or less than 20% of the catalyst area Acat of the cathode catalystlayer 6 b, as illustrated in FIG. 5A. If AOx is less than 5%, there isthe possibility that the oxidation gas distribution in the widthdirection M2 and the laminate layer direction of the membrane electrodeassembly 3 is reduced and that the ventilation pressure loss in theoxidation gas flow channel openings 11 is increased. Conversely, if AOxexceeds 20%, the volume of the fuel cell becomes large and, thus, is notpreferable.

The sum ARe of the cross-sectional area of the fuel gas flow channelopenings 9 is preferably equal to or greater than 5% and equal to orless than 20% of the catalyst area Acat of the anode catalyst layer 6 a.If ARe is less than 5%, there is the possibility that the fuel gasdistribution in the width direction M2 of the membrane electrodeassembly 3 is reduced and that the ventilation pressure loss in the fuelgas flow channel openings 9 is increased. Conversely, if ARe exceeds20%, the volume of the fuel cell becomes large and, thus, is notpreferable.

The number of oxidation gas flow channel openings 11 is preferablydivided into a plurality with respect to one active area (an area inwhich the catalyst layers 6 a, 6 b exist). The lower limit of thisnumber of divisions of the oxidation gas flow channel openings NOx ispreferably 2 or more, more preferably 5 or more, even more preferably 10or more, and even more preferably 15 or more. By configuring thedivisions of the NOx to be two or more, the oxidation gas can be moreeasily and evenly introduced by the membrane electrode assembly 3. Theupper limit of NOx is preferably 100 or less, more preferably 50 orless, even more preferably 30 or less, and even more preferably 20 orless. If NOx exceeds 100, there is little issue when the fuel cell isextremely large, but the area of the sealing material required for eachoxidation gas flow channel opening 11 becomes large. Consequently, thereis the possibility that achieving miniaturization, which is an object ofthe present application, will be difficult. In FIGS. 5A and 5B, theoxidation gas flow channel openings 11 are divided into four sections inone of the long sides (width W) of the membrane electrode assembly 3.

As with the case of the oxidation gas flow channel openings 11, thelower limit of the number of divisions of the fuel gas flow channelopenings NRe is preferably 2 or more, more preferably 5 or more, evenmore preferably 10 or more, and even more preferably 15 or more. Theupper limit of NRe is preferably 100 or less, more preferably 50 orless, even more preferably 30 or less, and even more preferably 20 orless. In FIGS. 5A and 5B, the fuel gas flow channel openings 9 aredivided into four sections in one of the long sides (width W) of themembrane electrode assembly 3.

Widened Portion

The widened portion 8 is a flow channel for supplying oxidation gas orfuel gas to a catalyst layer that is disposed in front of the adjacentflow channel openings for different types of fluids. For example, byproviding a fixed gap (distance) L′ between the catalyst layers 6 a, 6 band the flow channel openings 9, 10, 11, the gap can be configured asthe widened portion, as illustrated in FIGS. 5B and 5C. Morespecifically, for example, the widened portion 8 in the oxidation gascorresponds to the site between the catalyst layers 6 a, 6 b (actually,the gas diffusion layers 5 a, 5 b disposed above the catalyst layers 6a, 6 b) and the sealing material 12 that surrounds the periphery of thefuel gas flow channel openings 9 and the cooling water flow channelopenings 10.

By providing such a widened portion 8, oxidation gas that flows out fromthe oxidation gas flow channel openings 11 is diffused in the widthdirection M2 of the membrane electrode assembly 3 through the widenedportion 8, as illustrated in FIG. 5C. Then, the diffused oxidation gasis evenly supplied to the gas diffusion layer 5 b and the catalyst layer6 b. Accordingly, efficiently generating power across the entire MEAactive area becomes possible.

The length L′ of the widened portion 8 is preferably equal to or greaterthan 5% and equal to or less than 20% of the flow channel length L ofthe catalyst layers 6 a, 6 b (including the gas diffusion layers 5 a, 5b) in the gas flow direction M1. If the length L′ of the widened portion8 is equal to or less than 5% of the flow channel length, the loss ofpressure for supplying oxidation gas or fuel gas in front of theadjacent different type flow channel openings becomes large and, thus,is not preferable. If exceeding 20% of the flow channel length,miniaturization of the fuel cell becomes difficult and, thus, is notpreferable.

In the present embodiment, the widened portion 8 may be divided inaccordance with the number of divisions of the flow channel openings 9,10, 11. For example, in FIG. 5C, the widened portion 8 is divided to beparallel to the flow channel direction M1 of the membrane electrodeassembly 3 by a widened portion dividing portion 14, which is configuredby protruding a portion of the sealing material 12 toward the gasdiffusion layers 5 a, 5 b. The number of divisions of this widenedportion 8 preferably matches the number of divisions of the flow channelopenings NOx. Then, in FIG. 5, the number of divisions of the widenedportion matches the number of divisions of the oxidation gas flowchannel openings and is set to four. With this type of division of thewidened portion 8, limiting the supply of fluid from each flow channelopening to a specific flow channel width becomes possible. As a result,even if there is a greater than expected variability in the supply offluid, the fluid can be evenly supplied with respect to the widthdirection M2 of the membrane electrode assembly 3.

Separator

The separator 2 in the unit cell 4 comprises a function to collect theelectrons that are removed from the anode side catalyst layer 6 a to thegas diffusion layer 5 a and sending them to an external load circuit;the separator also comprises a function to distribute the electrons thathave returned from the external load circuit to the gas diffusion layer5 b and transmitting them to the cathode side catalyst layer 6 b.Furthermore, the separator 2 in the unit cell 4 takes on a gas cutofffunction by adhering to the gas diffusion layer 5 when the surface onthe opposite side of the catalyst layer 6 side of the gas diffusionlayer 5 does not have a gas cutoff function. The separator 2 also takeson a temperature adjusting function (a cooling function) of the fuelcell by configuring a cooling layer (a cooling fluid channel) as needed.

The separator 2 is preferably a nonporous body having conductivitybetween the front and back of the separator 2 and, more preferably, is ametal foil, such as aluminum foil, gold foil, nickel foil, copper foil,and stainless steel foil, or a carbon foil configured from a carbonmaterial, such as natural graphite. When configured from a metalmaterial besides a noble metal, there are cases in which an oxide filmis formed on the surface, increasing the electric resistance. To avoidthis, a surface layer consisting of one of the noble metals, such asgold, platinum, or palladium, a conductive carbon material, a conductiveceramic, or a conductive plastic is preferably disposed on the surfaceof the metal material, using a technique known to a person skilled inthe art. For example, a noble metal surface layer can be formed usingwell-known means, such as plating or sputtering. Furthermore, regardingthe carbon material surface layer, of the known technology referred toas DLC (Diamond-Like Carbon), especially those rich in SP2, having astructure similar to graphite and high conductivity, are widely used.Providing a base layer of chromium, etc. for the purpose of stabilizingthese surface layers is also known.

In FIG. 3, a plurality of flow channel openings are disposed on theouter peripheral part of the two opposing sides of the separator 2, butflow channel openings are not necessarily disposed in the separator. Forexample, a carrier sheet made of resin having flow channel openings isdisposed along the outer edge of a separator having the same planarshape as the catalyst layer 6. Then, the outer edge of the separator andthe inner edge of the carrier sheet are hermetically sealed. The samefunction as the separator in FIG. 3 can thereby be expressed. Thefunction of the flow channel openings of the separator 2 is equivalentto the function of the flow channel openings of the membrane electrodeassembly 3.

Flow Channel

A flow channel 13 for circulating oxidation gas or fuel gas can beformed on the surface of the separator 2, as illustrated in FIG. 6A.Additionally, a flow channel (not shown) for circulating a coolanttherein can be formed in the separator 2, if necessary.

The cross-sectional shape of the flow channel disposed in the separator2 is formed from convex portions referred to as ribs and concaveportions referred to as channels. Of these, electrons generated in thecatalyst layer are collected by the ribs coming in contact with the gasdiffusion layer. In FIG. 6B, reference codes “a,” “b,” and “c” indicatethe flow channel height of the flow channel 13 (the height of the ribs),the channel width of the flow channel 13, and the rib width of the flowchannel 13, respectively.

In the flow channel disposed inside of the cell laminate body 20, therib width c is defined by the arithmetic average of the width of the ribupper end and the width of the rib lower end. The lower limit of the ribwidth c is preferably 10μ or greater, is more preferably 50μ or greater,is even more preferably 100μ or greater, and is even more preferably200μ or greater. The upper limit of the rib width c is preferably 1000μor less, is more preferably 500μ or less, is even more preferably 400μor less, and is even more preferably 300μ or less. The object of thepresent invention can be achieved even if the rib width c is narrowerthan 10μ, so a significant problem does not occur; however, theprocessing means may be limited. When the rib width c exceeds 1000μ,there are cases in which oxidation gas or fuel gas cannot besufficiently supplied to the portion that comes in contact with the ribsvia the gas diffusion layer, of the catalyst layer surfaces. The lowerlimit of the rib height a is preferably 10μ or greater, is morepreferably 50μ or greater, is even more preferably 100μ or greater, iseven more preferably 125μ or greater, and is most preferably 150μ orgreater. The upper limit of the rib height a is preferably 1000μ orless, is more preferably 500μ or less, is even more preferably 300μ orless, is even more preferably 200μ or less, and is most preferably 180μor less. When the rib height a is less than 10μ, there are cases inwhich the flow channel area becomes small and the pressure lossincreases excessively. When the rib height a is higher than 1000μ, thereare cases in which the flow channel cross-sectional area becomes largeand the pressure loss decreases excessively. In a fuel cell in whichreaction water is generated accompanying driving, an operation isgenerally performed to constantly discharge with oxidation gas or fuelgas, so that the generated water does not stay in the flow channel, byapplying a predetermined pressure loss in the flow channel.

In the flow channel disposed inside of the cell laminate body 20, achannel is a space sandwiched between ribs. The channel width b isdefined by the arithmetic average of the width of the channel upper endand the width of the channel lower end. The lower limit of the channelwidth b is preferably 10μ or greater, is more preferably 50μ or greater,is even more preferably 100μ or greater, and is even more preferably200μ, or greater. The upper limit of the channel width b is preferably1000μ or less, is more preferably 500μ or less, is even more preferably400μ or less, and is even more preferably 300μ or less. Even if the gasflow amount and the ratio of the widths of the ribs and channels are thesame, if the channel width b is narrower than 10μ, there are cases inwhich the effects of the surface friction of the ribs becomes great andthe pressure loss increases too much. If the channel width b is greaterthan 1000μ, there are cases in which the flow channel area expands orcontracts too much when pressure difference is generated between the twosides of the membrane electrode assembly 3.

The horizontal shape of the flow channel 13 is preferably formed in alinear shape that connects the two opposing sides of the substantiallyrectangular catalyst layers at the shortest distance. In this case, forexample, when oxidation gas is supplied from the oxidation gas flowchannel openings 11 on the upper side, the oxidation gas is diffused inthe width direction M2 through the upper side widened portion 8 andthereafter flows downward through the flow channel 13, which is parallelto the gas flow direction M1, as illustrated in FIG. 5B. Then, theoxidation gas is discharged from the oxidation gas flow channel openings11, disposed on the lower side, through the lower side widened portion8. Accordingly, oxidation gas can be efficiently dispersed in the gasdiffusion layer 5 b and the cathode catalyst layer 6 b.

The flow channel 13 may be configured as a straight or a curved linethat is equal to or greater than the shortest distance, within a rangethat does not inhibit the object of the present invention. In thisembodiment, since fuel gas and oxidation gas necessary for the fuel cellreaction are evenly distributed across the entire surface of thecatalyst layer via the gas diffusion layer, the entire surface of thecatalyst layer can be covered.

Examples of manufacturing methods for the flow channel 13 includewell-known means such as press working and cutting.

The flow channel 13 in which the reaction gas circulates may be formedby ribs and channels on the surface of the separator 2, as describedabove. However, the present invention is not limited to this; the samefunction as the flow channel 13 has can be imparted to the gas diffusionlayers 5 a, 5 b of the membrane electrode assembly 3. For example,grooves that exert the same function as the flow channel 13 can beformed in the gas diffusion layers 5 a, 5 b. In this embodiment, sincethere is no need to form a flow channel 13 comprising the ribs andchannels described above on the surface of the separator 2, theseparator can be made to be smooth. The flow channel described above maybe disposed in both the gas diffusion layers 5 a, 5 b and the separator2.

Electrolyte Membrane

The electrolyte membrane 7 is a type of permselective film comprising afunction to transport protons and insulate electrons. The electrolytemembrane 7 is broadly divided into fluorine-based electrolyte membranesand hydrocarbon-based electrolyte membranes, depending on the type ofthe ion exchange resin, which is the constituent material. Of these,fluorine-based electrolyte membranes have excellent heat resistance andchemical stability due to having a C—F bond. For example, aperfluorosulfonic acid membrane known by the product name NATION(registered trademark, manufactured by DuPont) is widely used as theelectrolyte membrane 7.

Catalyst Layer

The cathode catalyst layer 6 b is a layer comprising an ionomer and anelectrode catalyst, in which a catalyst component is held. The electrodecatalyst comprises a function to promote a reaction that generates waterfrom protons, electrons, and oxygen (oxygen reduction reaction). Theelectrode catalyst comprises a structure in which a catalyst component,such as platinum, is held on the surface of a conductive carrierconsisting of, for example, carbon.

The anode catalyst layer 6 a is a layer comprising an electrodecatalyst, in which a catalyst component is held, and an ionomer. Theelectrode catalyst comprises a function to promote a reaction thatdissociates hydrogen into protons and electrons (hydrogen oxidationreaction). The electrode catalyst comprises a structure in which acatalyst component such as platinum is held on the surface of aconductive carrier consisting of, for example, carbon.

Internal Manifold

The fuel gas flow channel openings 9, the cooling water flow channelopenings 10, and the oxidation gas flow channel openings 11 disposed onthe long sides of the outer peripheral part of the membrane electrodeassembly 3 or the separator 2 are mutually connected to the flow channelopenings 9, 10, 11 included in the adjacent unit cell 4, following thelamination of the unit cells 4. Plural internal manifolds 21 (22, 23,24) with the same length as the cell laminate body 20 are therebyconfigured for each fluid, as illustrated in FIG. 2. Reference code “22”indicates internal manifolds for fuel gas formed by stacking fuel gasflow channel openings 9; reference code “23” indicates internalmanifolds for cooling water formed by stacking cooling water flowchannel openings 10; and reference code “24” indicates internalmanifolds for oxidation gas formed by stacking oxidation gas flowchannel openings 11. Each of the internal manifolds 22, 23, and 24includes a fluid-supplying internal manifold 21 and a fluid-discharginginternal manifold 21.

When describing the internal manifold 21, distinguishing between thosefor fluid-supplying and for fluid-discharging, the letter “a” isappended to the reference codes of those for fluid-supplying, which arereferred to as fluid-supplying internal manifolds 22 a, 23 a, 24 a.Also, the letter “b” is appended to the reference codes of those forfluid-discharging, which are referred to as fluid-discharging internalmanifolds 22 b, 23 b, 24 b.

Two or more fuel gas flow channel openings 9 are disposed in each of thetwo ends of the fuel gas flow channel, and two or more oxidation gasflow channel openings 11 are disposed in each of the two ends of theoxidation gas flow channel. Two or more cooling water flow channelopenings 10 are also disposed in each of the two ends of the coolingfluid channel. Accordingly, two or more fluid-supplying internalmanifolds 21 and fluid-discharging internal manifolds 21 are formed inthe cell laminate body 20 for each fluid.

The number of flow channel openings 9, 10, 11, and internal manifolds22, 23, 24 may be increased according to the aspect ratio R. That is,three or more fluid-supplying internal manifolds 21 andfluid-discharging internal manifolds 21 may be provided for each fluid.This is because the distribution ability can be improved by increasingthe number according to the aspect ratio R.

External Manifold

External manifolds 41 (a collective term for 42, 43, 44) for supplyingor discharging each fluid with respect to the cell laminate body 20 aredisposed outside of the cell laminate body 20, as illustrated in FIG. 1.The reference code “42” indicates external manifolds for fuel gas,reference code “43” indicates external manifolds for cooling water, andreference code “44” indicates external manifolds for oxidation gas. Theexternal manifolds 42, 43, 44 include fluid-supplying external manifolds41, which are connected to the fluid-supplying internal manifolds 21 viaa supply-side communicating portion 50 a, and fluid-discharging externalmanifolds 41, which connect to the fluid-discharging internal manifolds21 via a discharge-side communicating portion 50 b, for each fluid, asillustrated in FIG. 9-FIG. 11.

When describing the external manifold 41, when distinguishing betweenthose for fluid-supplying and for fluid-discharging, the letter “a” isappended to the reference codes of those for fluid-supplying, which arereferred to as the fluid-supplying external manifolds 42 a, 43 a, 44 a.Also, the letter “b” is appended to the reference codes of those forfluid-discharging, which are referred to as the fluid-dischargingexternal manifolds 42 b, 43 b, 44 b.

External manifolds 41 are disposed outside of the cell laminate body 20for each fluid in order to connect with the internal manifolds 21 tosupply or discharge the necessary fluids to the fuel cell. The externalmanifolds 41 comprise a plurality of supply-side communicating portions50 a and discharge-side communicating portions 50 b for connecting witha plurality of internal manifolds 21. The external manifolds 41 furthercomprise an inlet and an outlet for connecting with a fluid deviceoutside of the fuel cell stack and for supplying or discharging fluids.

As illustrated schematically in FIG. 10, the respective fluid-supplyingexternal manifold 42 a (43 a, 44 a) and fluid-discharging externalmanifold 42 b (43 b, 44 b) are positioned approximately in parallel,extending in the width direction of the cell laminate body 20. In thefluid-supplying and fluid-discharging external manifolds 41 (42, 43,44), the inlet and the outlet are preferably opened on the same surface.In addition to the center lines being perfectly parallel to each other,“parallel” must be interpreted as including cases in which the extensionlines from the center lines intersect while inclining from a parallelstate, to the extent that an improvement in the distribution ability canbe achieved, which is an object of the present invention.

The supply-side communicating portions 50 a comprise at least a firstauxiliary manifold 51 a, which is connected to the fluid-supplyinginternal manifolds 22 a, 23 a, 24 a, and a second auxiliary manifold 52a, which comprises a center line that intersects with the center linesof the fluid-supplying external manifolds 42 a, 43 a, 44 a, as well asthe center line of the first auxiliary manifold 51 a, and which isconnected to the fluid-supplying external manifolds 42 a, 43 a, 44 a, asillustrated in FIG. 9-FIG. 11. Similarly, the discharge-sidecommunicating portions 50 b comprise at least a first auxiliary manifold51 b, which is connected to the fluid-supplying internal manifolds 22 b,23 b, 24 b, and a second auxiliary manifold 52 b, which comprises acenter line that intersects with the center lines of the fluid-supplyingexternal manifolds 42 b, 43 b, 44 b, as well as the center line of thefirst auxiliary manifold 51 b, and which is connected to thefluid-supplying external manifolds 42 b, 43 b, 44 b, as illustrated inFIG. 9-FIG. 11. The supply-side communicating portions 50 a and thedischarge-side communicating portions 50 b may be collectively referredto as the “communicating portions 50;” the first auxiliary manifolds 51a, 51 b may be collectively referred to as the “first auxiliarymanifolds 51;” and the second auxiliary manifolds 52 a, 52 b may becollectively referred to as the “second auxiliary manifolds 52.”

The center line of the second auxiliary manifolds 52 of thecommunicating portions 50 intersects with the center line of theexternal manifolds 41 and intersects the center line of the firstauxiliary manifolds 51 that are connected to the internal manifolds 21,as illustrated in FIG. 10. In addition to the center lines beingorthogonal to each other, “intersect” must be interpreted as includingcases in which the center lines intersect while inclining from anorthogonal state, to the extent that an improvement in the distributionability can be achieved, which is an object of the present invention.

The configuration described above is characterized by each fluid flowingwhile substantially crossing more than once in the communicatingportions 50 between the external manifolds 41 and the internal manifolds21. Here, “substantially crossing more than once” means that a crossingof the central flux line is directly or indirectly observedsubstantially twice in the two pipes referred to as the externalmanifold 41 and the internal manifold 21 when fluid is circulatedbetween pipes of each other via the communicating portion 50. Here,“directly or indirectly observed” means confirming the flow of fluids byexperiment or simulation.

However, for example, the following type of connection is not consideredas “substantially crossing more than once.” That is, a case in which twopipes are put in contact so as to be orthogonal, cutting the contactportion so that the center line of one will be included in the pipe ofthe other, and providing a through port in the form of deeply meshingwith each other. In this connection form, the central flux line is bentsubstantially twice but is only skewed and cannot achieve an improvementin the distribution ability; thus, this is not considered to becrossing.

In a fuel cell comprising a low-aspect structure and comprising two ormore fluid-supplying internal manifolds 21 and fluid-discharginginternal manifolds 21 for each fluid, various necessary fluids for thefuel cell can be evenly supplied or discharged in the width direction ofthe unit cells 4, as well as in the laminate layer direction, whilesuppressing drift, by providing a distribution mechanism for flowingeach fluid between the external manifolds 41 and the internal manifolds21 while substantially crossing more than once. As a result, efficientlygenerating power becomes possible, and providing a compact, high-outputfuel cell becomes possible.

The external manifolds 41 are preferably disposed so that the centerline is offset inward of the center line of the internal manifolds 21(refer to FIG. 8-FIG. 10). This is because, when compared to disposingthe external manifolds 41 outside of the cell laminate body 20 whenviewed from the laminating direction of the unit cells 4, the volumeoccupied by the fuel cell can be reduced, and the degree of freedom inthe vehicle layout can be increased.

When the external manifold 44 of the oxidation gas, the externalmanifold 43 of the cooling water, and the external manifold 42 of thefuel gas are disposed overlapping in the laminate layer direction of theunit cells 4 in the cell laminate body 20, disposing the externalmanifold 43 of the cooling water between the external manifold 44 of theoxidation gas and the external manifold 42 of the fuel gas ispreferable, since temperature control of the oxidation gas and the fuelgas is facilitated. In general, the closer the external manifolds 41(42, 43, 44) are disposed to the cell laminate body 20, the longer theinlet length for the fluid that flows in the external manifolds 41 toflow in or flow out with respect to the cell laminate body 20, that is,the longer the distance of the communicating portion 50, specificallythe distance of the first auxiliary manifold 51, can be; as a result,the flow of the fluid is stabilized, and drifting of the fluid in theinternal manifolds 21 (22, 23, 24) can be reduced. When drifting of thefluid in the internal manifolds 21 is reduced, each fluid is evenlydistributed to the respective unit cells 4, and the efficiency of thefuel cell 1 is increased, which is preferable. Here, since drift in theinternal manifolds 21 is reduced as the speed of the fluid is decreasedat the same time as the inlet length, reducing drifting is possible ifthe cross-sectional area of the first auxiliary manifold 51 s or theinternal manifold 21 s is large, even when the inlet length is short. Aperson skilled in the art can appropriately determine the placement ofthe external manifolds 42, 43, 44 based on the relationship between theinlet length and the cross-sectional area.

The external manifolds 41 may be provided for the fuel gas, the coolingwater, and the oxidation gas. For each fluid, the external manifolds 41(42, 43, 44) and the first and second auxiliary manifolds 51, 52 in thecommunicating portions 50 are preferably disposed inside of an end plate32 (or 31). This is because miniaturization of the fuel cell can beachieved by integrating the external manifolds 41 and the communicatingportions 50 into the end plate 32 (or 31).

Minimizing the volume of the fluid distribution device is also possibleby configuring all of the external manifolds 41 of the fuel gas, thecooling water, and the oxidation gas, as well as all the first andsecond auxiliary manifolds 51, 52 in the communicating portions 50, tobe inside of one of the end plates 32 (or 31). In this embodiment, theexternal manifold 44 for the oxidation gas is preferably disposed on thelayer closest to the cell laminate body 20; the external manifold 42 forthe fuel gas is preferably disposed on the farther layer; and theexternal manifold 43 for the cooling water is preferably disposed inbetween. This is because, when configuring an end plate 32 (three-stepmonocoque end plate 32) comprising three layers of external manifolds42, 43, 44, the cooling water is circulated between the fuel gas and theoxidation gas; therefore, maintaining the temperature of each fuel cellfluid becomes easy, which is preferable.

The ratio of the cross-sectional area of the discharge-side pipe and thecross-sectional area of the supply-side pipe of the external manifolds41 may be the same or different, depending on the purpose. However, in acathode that uses cooling water and air, the discharge-sidecross-sectional area of the external manifolds 43, 44 is preferablylarger than the cross-sectional area of the supply-side. Of the fluidssupplied to the fuel cell, the cooling water is not consumed duringpower generation. Also, when using air as the oxidation gas, whileoxygen is consumed, nitrogen is not consumed, so the amount of decreaseis smaller as compared to the fuel gas in the anode. This is because, ina fluid in which the flow amount does not change during the flow or inwhich the amount of decrease is small, pressure loss on the dischargeside can be reduced, and the distribution ability can be improved byconfiguring the discharge-side cross-sectional area to be larger thanthe supply-side cross-sectional area.

In a fuel gas that is consumed during the flow, the magnituderelationship of the discharge-side and supply-side cross-sectional areascannot be categorically set; however, a person skilled in the art wouldbe able to appropriately determine this from the above point of view,based on the actual change in the flow amount on the discharge-side andthe supply-side. Also, using oxygen instead of air as the oxidation gasis the same as using fuel gas.

The respective openings of the external manifolds 42, 43, 44 may beopened on the same fuel cell stack side or on the opposite side of thefuel cell stack, with respect to the respective fluids. However, each ofthe inlets and outlets of the external manifolds 42, 43, 44 ispreferably open on the same surface. In the present invention, openingthe inlets and outlets on the same surface is referred to as a U-flow,and opening the inlets and outlets on opposite surfaces is referred toas a Z-flow, based on having a similar shapes as these letters. In thepresent invention, the U-flow is preferable; if the Z-flow is used,there are cases in which unevenness in the flow amount occurs easily inthe width direction of the cell laminate body in each of the internalmanifolds and in each of the flow channels. In the first embodiment, theexternal manifolds 42, 43, 44 for the fuel gas, the cooling water, andthe oxidation gas, as well as a communicating portion 50, are disposedin the same end plate 32. Of the opposing sides of the end plate 32, theinlet and the outlet of the external manifold 42 for the fuel gas areopen on the first side (the front left side in the drawing), and theinlet and the outlet of the external manifold 44 for the oxidation gasare open on the same first side, as illustrated in FIG. 1. The inlet andthe outlet of the external manifold 43 for the cooling water are open onthe second side on the opposite side. The external manifolds 41 areformed from through-holes that penetrate from the first side to thesecond side of the end plate 32. The openings on the second side of theexternal manifold 42 for the fuel gas and the external manifold 44 forthe oxidation gas are sealed by a closing plate after forming thethrough-holes. On the other hand, the opening on the first side of theexternal manifold 43 for the cooling water is sealed by a closing plate33 after forming the through-hole.

In addition to having a high volumetric output density, the fuel cell 1of the present embodiment has a high degree of freedom in thearrangement of the exit/entrance for supplying or discharging thenecessary fluids to the fuel cell 1; therefore, a good mountability andlayout ability can be provided.

End Plate

The cell laminate body 20 obtained by alternately stacking the membraneelectrode assembly 3 and the separator 2 is sandwiched by end plates 31,32 from both sides in the laminate layer direction. A fuel cell stack isthereby configured. Plural connection ports 34, 35, 36 are formed on thecontact surface with the cell laminate body 20 in the end plate 32, asillustrated in FIG. 8 and FIG. 9A. Various necessary fluids for the fuelcell 1 are supplied or discharged between the end plate 32 and theinternal manifolds 21 via these connection ports 34, 35, 36. Thereference code “34” indicates a connection port for fuel gas, referencecode “35” indicates a connection port for cooling water, and referencecode “36” indicates a connection port for oxidation gas.

Displacement Absorption Mechanism

A displacement absorption mechanism may be disposed in the fuel cell 1in order to absorb the dimensional changes of the cell laminate body 20in the laminate layer direction, such as swelling and contraction due tothe hydration and drying of the electrolyte membrane, in order tohomogenize the pressure distribution in the cell laminate body.Displacement absorption mechanisms known to a person skilled in the art,configured from an elastic body such as a disc spring or rubber, may beused as the displacement absorption mechanism. The displacementabsorption mechanism is preferably disposed on at least one of the endplates 31, 32 and inside or on the surface of the end plates 31, 32.

As described above, for each fluid, the external manifolds 42, 43, 44and the first and second auxiliary manifolds 51, 52 in the communicatingportions 50 are preferably disposed inside of the end plate 32 (or 31).

Fluid Distribution Device

The fluid distribution device 100 of the first embodiment comprises ablock body 60, in which are formed external manifolds 41 (42, 43, 44),and the first and second auxiliary manifolds 51 (51 a, 51 b), 52 (52 a,52 b) of the communicating portions 50 (50 a, 50 b) in each of thefluids, as illustrated in FIGS. 9A and 9B. The block body 60 configuresone of the end plates 32.

If the surface on the side of the block body 60 to which the celllaminate body 20 is disposed were to be one surface 62, the externalmanifold 44 for the first fluid that flows on the side closer to the onesurface 62 and the external manifold 42 for the second fluid that flowson the side farther from the one surface 62 are disposed partiallyoverlapping when viewed from the one surface 62 side of the block body,as indicated by the arrow 61. Additionally, when viewed from the onesurface 62 side of the block body 60, the external manifold 43 for thethird fluid comprises an extension portion 63 that does not overlap withthe external manifold 44 for the first fluid, and the external manifold42 for the second fluid comprises an extension portion 64 that does notoverlap with the external manifold 43 for the third fluid. The onesurface 62 of the block body 60 is connected to the end surface of thecell laminate body 20. In the case of the first embodiment, the firstfluid is oxidation gas, the second fluid is fuel gas, and the thirdfluid is cooling water, as described above.

The first and second auxiliary manifolds 51, 52 in the communicatingportions 50 are formed in the following manner.

Regarding the supply-side communicating portion 50 a for the first fluid(oxidation gas), a first hole portion 71 that communicates only to theexternal manifold 44 a for the first fluid is formed from the onesurface 62 side, as illustrated in FIG. 11C. A portion of the side wallthat forms a partition in the external manifold 44 a for the first fluidis removed by the first hole portion 71, and first and second auxiliarymanifolds 51 a, 52 a for the first fluid are formed.

Regarding the discharge-side communicating portion 50 b for the firstfluid, a first hole portion 71 that communicates only to the externalmanifold 44 b for the first fluid is formed from the one surface 62side, as illustrated in FIG. 11A. A portion of the side wall that formsa partition in the external manifold 44 b for the first fluid is removedby the first hole portion 71, and first and second auxiliary manifolds51 b, 52 b for the first fluid are formed.

Regarding the supply-side communicating portion 50 a for the secondfluid (fuel gas), a second hole portion 72 that communicates only to theexternal manifold 42 a for the second fluid in the extension portion 64(refer to FIG. 9B) is formed from the one surface 62 side, asillustrated in FIG. 11C. A portion of the side wall that forms apartition in the external manifold 42 a for the second fluid is removedby the second hole portion 72, and first and second auxiliary manifolds51 a, 52 a for the second fluid are formed.

Regarding the discharge-side communicating portion 50 b for the secondfluid, a second hole portion 72 that communicates only to the externalmanifold 42 b for the second fluid is formed from the one surface 62side, as illustrated in FIG. 11A. A portion of the side wall that formsa partition in the external manifold 42 b for the second fluid isremoved by the second hole portion 72, and first and second auxiliarymanifolds 51 b, 52 b for the second fluid are formed.

Regarding the supply-side communicating portion 50 a for the third fluid(cooling water), a third hole portion 73 that communicates only to theexternal manifold 43 a for the third fluid in the extension portion 63(refer to FIG. 9B) is formed from the one surface 62 side, asillustrated in FIG. 11B. A portion of the side wall that forms apartition in the external manifold 43 a for the third fluid is removedby the third hole portion 73, and first and second auxiliary manifolds51 a, 52 a for the third fluid are formed.

Regarding the discharge-side communicating portion 50 b for the thirdfluid, a third hole portion 73 that communicates only to the externalmanifold 43 b for the third fluid in the extension portion 63 is formedfrom the one surface 62 side, as illustrated in FIG. 11B. A portion ofthe side wall that forms a partition in the external manifold 43 b forthe third fluid is removed by the third hole portion 73, and first andsecond auxiliary manifolds 51 b, 52 b for the third fluid are formed.

An inclined surface that is inclined from the one surface 62 toward thehole portions 72, 73 is formed in the upper portion of the second holeportion 72 and the third hole portion 73. The size of the connectionport 34 for fuel gas and the connection port 35 for cooling water in theleft-right direction in FIG. 11 is thereby set to be the same size asthe connection port 36 for the oxidation gas.

The fluid distribution device 100 forms the external manifolds 41 andthe communicating portions 50 in a block body 60 that configures the endplate 32; as a result, miniaturization of the fuel cell 1 can beachieved. In addition, since the external manifolds 41 and the first andsecond auxiliary manifolds 51, 52 in the communicating portions 50 canbe formed by cutting operations, the manufacturing of the fluiddistribution device 100 can be simplified and can be performedinexpensively, as compared to assembling by welding and joining numerousparts.

Mechanism of the Fuel Cell

The mechanism of the fuel cell 1 is as follows. That is, protons andelectrons are generated from hydrogen that is supplied to the anodecatalyst layer 6 a. The protons generated in the anode move inside ofthe electrolyte membrane 7 and reach the cathode catalyst layer 6 b.Meanwhile, the electrons generated in the anode are taken out of thefuel cell along a conductive wire (conductor). Then, after consumingelectricity in an external load circuit, the above-described electronsreturn to the cathode along the conductive wire (conductor) and reactwith the oxygen supplied to the cathode catalyst layer 6 b to generatewater’.

Operation of the Fuel Cell

The operation of the fuel cell 1 is performed by supplying hydrogen toone electrode (anode) and oxygen or air to the other electrode(cathode). The higher the operating temperature of the fuel cell, themore the catalyst activity increases and, thus, is preferable; however,normally, the operation is often conducted at 50° C.-100° C., at whichtemperature moisture management is easy.

Vehicle Equipped with a Fuel Cell

FIGS. 12A and 12B are views illustrating an example of a vehicleequipped with the fuel cell of the present embodiment. The vehicle 18illustrated in FIG. 12A is equipped with the fuel cell 1 of the presentembodiment as a drive source in the engine bay. The vehicle 18illustrated in FIG. 12B is equipped with the fuel cell 1 of the presentembodiment as a drive source below the floor. For example, polymerelectrolyte fuel cells (PEFC) and stacked fuel cells to which thepresent invention is applied have extremely excellent outputperformances and are, thus suitable for vehicle applications, whichrequire high output.

Layout of the Cell Laminate Body 20 and the External Manifolds 41

FIG. 13A, FIG. 13B, and FIG. 13C are views schematically illustratingexamples of the layouts of the cell laminate body 20 and the externalmanifolds 41.

In the fuel cell illustrated in FIG. 13A, an internal manifold 24 isdisposed in the vertical direction, and an external manifold 44 thatconnects to the internal manifold 24 is disposed below the cell laminatebody 20, at least in the cathode. The cell laminate body 20 isconfigured so that the unit cells 4 are arranged along the horizontaldirection. According to this kind of layout, generated water can bereliably discharged via gravity, and a fuel cell that maintains aflooding resistance ability can be provided.

In the fuel cell illustrated in FIG. 13B, an internal manifold 24 isdisposed in the horizontal direction, and an external manifold 44 thatconnects to the internal manifold 24 is disposed below internal manifold24, at least in the cathode. The cell laminate body 20 is configured sothat the unit cells 4 are arranged along the vertical direction. Evenaccording to this kind of layout, generated water can be reliablydischarged via gravity, and a fuel cell that maintains a floodingresistance ability can be provided.

In the fuel cell illustrated in FIG. 13C, an external manifold 44 isdisposed in the vertical direction, and an internal manifold 24 thatconnects to the external manifold 44 is disposed in the horizontaldirection, at least in the cathode. The cell laminate body 20 isconfigured so that the unit cells 4 are arranged along the verticaldirection.

In a fuel cell stack, smoothly removing the generated water accompanyingthe fuel cell reaction from the fuel cell stack via a flow channel is aproblem that should always be considered when maintaining stable powergeneration. In FIGS. 13A-13C, the flow channel direction is thehorizontal direction in FIG. 13A or FIG. 13C, so that generated watercan be smoothly discharged out of the fuel cell stack via the flowchannels, regardless of whether the oxidation gas and the hydrogen gasare flowing parallel or opposite to each other. On the other hand, theflow channel direction is the vertical direction in FIG. 13B, so that,when the oxidation gas and the hydrogen gas are flowing in oppositedirections of each other, the flow of one gas will always flowvertically from the bottom to the top; as a result, there are cases inwhich the generated water cannot be smoothly discharged out of the fuelcell stack via the flow channels when the flow rate of the gas is slow.In this embodiment, the generated water can be smoothly discharged bysetting both the oxidation gas and the hydrogen gas to flow verticallyfrom the top to the bottom as parallel flows. In general, the oxidationgas and the hydrogen gas are preferably flowing opposite directions ofeach other in a fuel cell reaction; thus, FIG. 13A or FIG. 13C is morepreferable than FIG. 13B.

Next, when comparing FIG. 13A and FIG. 13C, the internal manifold 24 isdisposed in the vertical direction in FIG. 13A while the internalmanifold 24 is disposed in the horizontal direction in FIG. 13C. Since,in general, an internal manifold 24 disposed in the vertical direction,which can utilize gravity, has a better draining ability, FIG. 13A ismore preferable than FIG. 13C. However, since the draining ability canbe improved by various means besides gravity, such as by the flow rateof the gas and surface treatments, the layout of FIGS. 13A-13C ispreferably selected not only with respect to the draining ability butalso through a comprehensive determination. For example, when thelaminate layer direction of the fuel cell stack is longer than the widthdirection (longitudinal direction) of the unit cells 4, the height ofthe fuel cell stack when being mounting to a vehicle can be kept low byemploying the layout FIG. 13C. This is preferable in many cases in termsof vehicle design. Also, if the layout of FIG. 13A is employed and thewidth direction of the unit cells 4 is laid out in the same direction asthe width direction of the vehicle, the longitudinal direction of thefuel cell stack in the vehicle can be shortened; as a result, a largecrush zone volume in the event of collision can be secured.

Effects of the Present Embodiment

As described above, the fuel cell 1 of the first embodiment comprises alow-aspect structure, and the pressure loss when transporting necessaryfluids to the fuel cell becomes physically lower than in a fuel cellcomprising a high-aspect structure having the same cell pitch.Accordingly, when transporting at a constant pressure loss,miniaturization of the fuel cell can be achieved by using a smaller cellpitch. The fuel cell 1 according to the present invention comprises twoor more fluid-supplying internal manifolds 21 and fluid-discharginginternal manifolds 21 for each fluid. Accordingly, the various necessaryfluids for the fuel cell 1 can be evenly supplied or discharged in thewidth direction of the unit cells 4, and the effect thereof isproportional to the number of the internal manifolds 21.

Additionally, a fluid-supplying external manifold 42 a (43 a, 44 a),which is connected to the fluid-supplying internal manifold 22 a (23 a,24 a) via the supply-side communicating portion 50 a, and afluid-discharging external manifold 42 b (43 b, 44 b), which isconnected to the fluid-discharging internal manifold 22 b (23 b, 24 b)via the discharge-side communicating portion 50 b, are positionedoutside of the cell laminate body 20 approximately parallel to eachother, extending in the width direction of the cell laminate body 20.The entire fuel cell 1 can thereby be configured to be compact. As aresult, providing a compact, high-output fuel cell 1 becomes possible.

The fluid-supplying and fluid-discharging external manifolds 41 (42, 43,44) comprise openings at the ends in the same direction. The openingsconfiguring the inlets and the openings configuring the outlets in theexternal manifolds 41 are open on the same surface. When compared towhen opening the inlets and the outlets on opposite sides, thegeneration of unevenness in the flow amount in the width direction ofthe cell laminate body 20 in the internal manifolds 21 (22, 23, 24) andthe flow channels can be suppressed.

A fluid distribution mechanism is provided for passing each of thefluids between the external manifolds 41 and the internal manifolds 21while substantially crossing more than once. Accordingly, the variousnecessary fluids for the fuel cell 1 can be evenly supplied ordischarged in the width direction and the laminate layer direction ofthe unit cells 4 while suppressing drift in the laminate layer directionin the internal manifolds. As a result, efficiently generating powerbecomes possible, and providing a compact, high-output fuel cell alsobecomes possible from this point of view.

The center line of the external manifolds 41 is offset to be inward ofthe center line of the internal manifolds 21. Accordingly, when comparedto when disposing the external manifolds 41 outside of the cell laminatebody 20, when viewed from the laminating direction of the unit cells 4,the volume occupied by the fuel cell can be reduced, and the degree offreedom in the layout can be increased.

Drift in the laminate layer direction in the internal manifolds 22, 23,24 tends to occur in portions close to the fluid distribution device 100immediately after connecting from the external manifold to the internalmanifold via the communicating portion 50; this drift becomes moresignificant as the cross-sectional areas of the first and secondauxiliary manifolds 51, 52 and the internal manifolds 21 decrease and asthe flow amount increases. Whether the external manifold 44 of thecathode or the external manifold 42 of the anode moves to the positionnear the cell laminate body 20 cannot be categorically determined;however, a person skilled in the art would be able to appropriatelydetermine this from the above point of view, based on thecross-sectional areas of the first and second auxiliary manifolds 51, 52and the internal manifolds 21, as well as the flow amount.

For example, the external manifold 44 of the cathode and the externalmanifold 42 of the anode may be disposed overlapping, and the externalmanifold 44 of the cathode may be positioned closer to the cell laminatebody 20 than the external manifold 42 of the anode. In the embodiment ofthis arrangement, regarding the distance between the external manifolds42, 44 and the internal manifolds 22, 24, the flowing distance of thefuel gas can be set to be longer than the flowing distance of theoxidation gas. As a result, the inlet length of the fuel gas can be setto be long, and the fluids can be more evenly supplied or discharged inthe width direction and the laminate layer direction of the unit cells 4while suppressing drift in the laminate layer direction in the internalmanifolds 22, 24.

An arrangement that is the reverse of the illustrated embodiment is alsopossible; in other words, the external manifold of the cathode and theexternal manifold of the anode may be disposed to be overlapping, andthe external manifold of the cathode may be positioned farther from thecell laminate body 20 than the external manifold of the anode.

An internal manifold 24 is disposed in the vertical direction, and anexternal manifold 44 that connects to the internal manifold 24 isdisposed below the cell laminate body 20, at least in the cathode.Alternatively, an internal manifold 24 is disposed in the horizontaldirection, and an external manifold 44 that connects to the internalmanifold 24 is disposed below the internal manifold 24, at least in thecathode. According to this kind of layout, generated water can bereliably discharged via gravity, and a fuel cell that maintains aflooding resistance ability can be provided.

In each fluid, the external manifolds 41 and the first and secondauxiliary manifolds 51, 52 in the communicating portions 50 are disposedinside of the end plate 32. Miniaturization of the fuel cell 1 can beachieved by integrating the external manifolds 41 and the communicatingportions 50 into the end plate 32.

In a cathode that uses cooling water and air, the discharge-sidecross-sectional area of the external manifolds 43, 44 is set to belarger than the cross-sectional area of the supply-side. In a fluid inwhich the flow amount does not change while flowing or in which theamount of decrease is small, pressure loss on the discharge side can bereduced, and a good distribution ability can be achieved by configuringthe discharge-side cross-sectional area to be larger than thesupply-side cross-sectional area.

Three or more fluid-supplying internal manifolds 21 andfluid-discharging internal manifolds 21 may be provided for each fluid.The distribution ability can be improved by increasing the numberaccording to the aspect ratio R.

According to the fluid distribution device 100 of the fuel cell 1according to the first embodiment, the fluid-supplying externalmanifolds 42 a, 43 a, 44 a and the fluid-discharging external manifolds42 b, 43 b, 44 b are formed in a block body 60 that configures the endplate 32; as a result, miniaturization of the fuel cell 1 can beachieved. Furthermore, since the configuration of the communicatingportions 50 a, 50 b, which are adjacent to the external manifolds 42 a,43 a, 44 a, 42 b, 43 b, 44 b, is simple and can be easily formed bymeans such as a cutting operation, the manufacturing of the fluiddistribution device 100 can be simplified and can be performedinexpensively, as compared to when assembling by welding and joiningnumerous parts.

Since the vehicle 18 of the present embodiment comprises a miniaturizedfuel cell, the vehicle will have excellent mountability, productivity,and cost.

Second Embodiment

FIGS. 14A and 14B are a perspective view and a plan view illustratingthe fuel cell 80 according to a second embodiment; FIG. 15A is aperspective view illustrating a cross-section of the principle part ofthe lower side end plate 82 that incorporates a fluid distributiondevice 101 according to the second embodiment, and FIG. 15B is across-sectional view illustrating the lower side end plate 82 to whichan external manifold 41 is provided. FIGS. 16A and 16B arecross-sectional views illustrating states in which the first and thesecond auxiliary manifolds 51 a, 52 a in the supply-side communicatingportion 50 a, as well as the first and the second auxiliary manifolds 51b, 52 b in the discharge-side communicating portion 50 b, are formed foreach fluid in a block body 90 configuring the lower side end plate 82.Members common to the members illustrated in FIGS. 1-13C have been giventhe same reference codes, and the explanations thereof have beenomitted.

In the second embodiment, external manifolds 42, 43 of two fluids amongthe fuel gas, the cooling water, and the oxidation gas, along with acommunicating portion 50, are provided in the same lower side end plate82. The second embodiment is different in this point from the firstembodiment, in which the external manifolds 42, 43, 44 of all threefluids, as well as a communicating portion 50, are disposed in the sameend plate 32.

In the second embodiment, the external manifolds 42, 43 of the fuel gasand the cooling water, as well as a communicating portion 50, aredisposed in the lower side end plate 82, as illustrated on the lowerside of the drawing; the external manifold 44 of the oxidation gas, aswell as a communicating portion 50, are disposed in an upper side endplate 81, as illustrated on the upper side of the drawing. Of theopposing sides of the lower side end plate 82, the inlet and the outletof the external manifold 43 for the cooling water are open on the firstside (the front left side in the drawing), and the inlet and the outletof the external manifold 42 for the fuel gas are open on the secondside, which is on the opposite side, as illustrated in FIGS. 14 A and14B. The inlet and the outlet of the external manifold 44 for theoxidation gas are open on the first side of the upper side end plate 81.The external manifolds 41 are formed from through-holes that penetratefrom the first side to the second side of the end plates 81, 82. Theopenings on the second side of the external manifold 43 for the coolingwater and the external manifold 44 for the oxidation gas are sealed by aclosing plate after forming the through-holes. On the other hand, theopening on the first side of the external manifold 42 for the fuel gasis sealed by a closing plate 83 after forming the through-hole.

Regarding the lower side end plate 82, the supply-side communicatingportions 50 a comprise at least a first auxiliary manifold 51 a, whichis connected to the fluid-supplying internal manifolds 22 a, 23 a, and asecond auxiliary manifold 52 a, which comprises a center line thatintersects with the center lines of the fluid-supplying externalmanifolds 42 a, 43 a, as well as the center line of the first auxiliarymanifold 51 a, and which is connected to the fluid-supplying externalmanifolds 42 a, 43 a, as illustrated in FIGS. 15A and 15B and FIGS. 16Aand 16B. Similarly, the discharge-side communicating portions 50 bcomprise at least a first auxiliary manifold 51 b, which is connected tothe fluid-supplying internal manifolds 22 b, 23 b, and a secondauxiliary manifold 52 b, which comprises a center line that intersectswith the center lines of the fluid-discharging external manifolds 42 b,43 b, as well as the center line of the first auxiliary manifold 51 b,and which is connected to the fluid-discharging external manifolds 42 b,43 b.

Regarding the upper side end plate 81, while a diagram has been omitted,the center line of the second auxiliary manifolds 52 of thecommunicating portions 50 intersects with the center line of theexternal manifolds 44 and intersects with the center line of the firstauxiliary manifolds 51 that are connected to the internal manifolds 24.

In the second embodiment as well, in a fuel cell comprising a low-aspectstructure and comprising two or more fluid-supplying internal manifolds21 and fluid-discharging internal manifolds 21 for each fluid, variousnecessary fluids for the fuel cell 80 can be evenly supplied ordischarged in the width direction of the unit cells 4, as well as in thelaminate layer direction, by providing a distribution mechanism forpassing each fluid between the external manifolds 41 and the internalmanifolds 21 while substantially crossing more than once. As a result,efficiently generating power becomes possible, and providing a compact,high-output fuel cell becomes possible.

The fluid distribution device 101 of the second embodiment comprises ablock body 90, in which external manifolds 42, 43 are formed, and thefirst and second auxiliary manifolds 51 (51 a, 51 b), 52 (52 a, 52 b) ofthe communicating portions 50 (50 a, 50 b) in the fuel gas and thecooling water, as illustrated in FIG. 15. The block body 90 configuresthe lower side end plate 82.

If the surface on the side of the block body 90 to which the celllaminate body 20 is disposed were to be one surface 92, the externalmanifold 42 for the first fluid that flows on the side closer to the onesurface 92 and the external manifold 43 for the second fluid that flowson the side farther from the one surface 92 are disposed partiallyoverlapping, when viewed from the one surface 92 side of the block body90, as illustrated by the arrow 91. Additionally, the external manifold43 for the second fluid includes an extension portion 93 that does notoverlap with the external manifold 42 for the first fluid, when viewedfrom the one surface 92 side of the block body 90. The one surface 92 ofthe block body 90 is connected to the lower surface of the cell laminatebody 20. In the embodiment of the second embodiment, the first fluid isfuel gas, and the second fluid is cooling water. That is, since theoxidation gas external manifold 44 is disposed to the upper side endplate 81, there are cases in which water that is produced by thereaction of the fuel cell accumulates in the lower part of the oxidationgas internal manifold 24. In this embodiment, a drain hole may be formedfrom the lower part of the internal manifold 24 toward the outside ofthe block body 90.

On the other hand, the first fluid of the block body 90 may be fuel gas,and the second fluid may be oxidation gas, as a modified example of thesecond embodiment. In this embodiment, the external manifold 44 of thecooling water is disposed to the upper side end plate 81; however, sinceall of the manifolds and flow channels are constantly filled withcooling water, forming the drain hole is not necessary. However, sincethe fuel gas external manifold cannot be directly temperature controlledwith the cooling water external manifold, there are cases thatseparately require a device for controlling the temperature of the fuelgas.

The first and the second auxiliary manifolds 51, 52 in the communicatingportion 50 of each fluid are formed in the following manner.

Regarding the supply-side communicating portion 50 a for the first fluid(fuel gas), a first hole portion 94 that communicates only to theexternal manifold 42 a for the first fluid is formed from the onesurface 92 side, as illustrated in FIG. 16A. A portion of the side wallthat forms a partition in the external manifold 42 a for the first fluidis removed by the first hole portion 94, and first and second auxiliarymanifolds 51 a, 52 a for the first fluid are formed.

Regarding the discharge-side communicating portion 50 b for the firstfluid, a first hole portion 94 that communicates only to the externalmanifold 42 b for the first fluid is formed from the one surface 92side, as illustrated in FIG. 16A. A portion of the side wall that formsa partition in the external manifold 42 b for the first fluid is removedby the first hole portion 94, and first and second auxiliary manifolds51 b, 52 b for the first fluid are formed.

Regarding the supply-side communicating portion 50 a for the secondfluid (cooling water), a second hole portion 95 that communicates onlyto the external manifold 43 a for the second fluid in the extensionportion 93 (refer to FIG. 15B) is formed from the one surface 92 side,as illustrated in FIG. 16B. A portion of the side wall that forms apartition in the external manifold 43 a for the second fluid is removedby the second hole portion 95, and first and second auxiliary manifolds51 a, 52 a for the second fluid are formed.

Regarding the discharge-side communicating portion 50 b for the secondfluid, a second hole portion 95 that communicates only to the externalmanifold 43 b for the second fluid in the extension portion 93 is formedfrom the one surface 92 side, as illustrated in FIG. 16B. A portion ofthe side wall that forms a partition in the external manifold 43 b forthe second fluid is removed by the second hole portion 95, and first andsecond auxiliary manifolds 51 b, 52 b for the second fluid are formed.

An inclined surface that is inclined from the one surface 92 toward thehole portion 95 is formed in the upper portion of the second holeportion 95. The size of the connection port 35 for cooling water in theleft-right direction in FIG. 16 is thereby set to be the same size asthe connection port 34 for fuel gas.

According to the fluid distribution device 101 of the fuel cell 80according to the second embodiment, the external manifold 44 and thecommunicating portion 50 are formed in a block body that configures theupper side end plate 81, and the external manifolds 42, 43 and thecommunicating portion 50 are formed in a block body 90 that configuresthe lower side end plate 82; as a result, miniaturization of the fuelcell 80 can be achieved. In addition, since the external manifolds 41and the first and second auxiliary manifolds 51, 52 in the communicatingportions 50 can be formed by cutting operations, the manufacturing ofthe fluid distribution device 101 can be simplified and can be performedinexpensively, as compared to when assembling by welding and joiningnumerous parts.

When forming first and second auxiliary manifolds for the third fluid inthe block body 90, an appropriate arrangement is possible in accordancewith the configuration of the auxiliary manifolds for the first andsecond fluids.

Other Modified Examples

In the first embodiment, two or more flow channel openings 9 aredisposed in each of the two ends of the anode flow channel, wherein oneend is formed as a supply flow channel and the other end is formed as adischarge flow channel, and two or more flow channel openings 11 aredisposed in each of the two ends of the cathode flow channel, whereinone end is formed as a supply flow channel and the other end is formedas a discharge flow channel. The flow channel openings 9 in the anodeflow channel are laminated to configure the two or more fluid-supplyinginternal manifolds 22 a and the two or more fluid-discharging internalmanifolds 22 b. The flow channel openings 11 in the cathode flow channelare laminated to configure the two or more fluid-supplying internalmanifolds 24 a and the two or more fluid-discharging internal manifolds24 b.

The configuration to evenly supply or discharge various fluids in thewidth direction of the unit cells 4 is not limited to a configuration inwhich two or more flow channel openings 9, 10, 11 are disposed in eachof the two ends of the respective flow channels.

That is, the cell laminate body 20 may be configured so that the aspectratio R (L/W) is less than 1; so that two or more of at least one of theflow channel openings 9 at the two ends of the anode flow channel areprovided, wherein one end is formed as a supply flow channel and theother end is formed as a discharge flow channel; and so that two or moreof at least one of the flow channel openings 11 at the two ends of thecathode flow channel are provided, wherein one end is formed as a supplyflow channel and the other end is formed as a discharge flow channel.The flow channel openings 9 in the anode flow channel are laminated toconfigure the fluid-supplying internal manifolds 22 a and thefluid-discharging internal manifolds 22 b, and the flow channel openings11 in the cathode flow channel are laminated to configure thefluid-supplying internal manifolds 24 a and the fluid-discharginginternal manifolds 24 b. The external manifolds 42 a, 42 b, 44 a, 44 bthat are connected to the internal manifolds 22 a, 22 b, 24 a, 24 bextend in a direction that intersects with the internal manifolds 22 a,22 b, 24 a, 24 b.

Various fluids can also be evenly supplied or discharged in the widthdirection of the unit cells 4 in a fuel cell configured in this way.

In this embodiment, each of the fluid-supplying external manifolds 42 a,44 a that are connected to the fluid-supplying internal manifolds 22 a,24 a, as well as the fluid-discharging external manifolds 42 b, 44 bthat are connected to the fluid-discharging internal manifolds 22 b, 24b, is positioned extending in the width direction of the cell laminatebody 20. The entire fuel cell can thereby be configured to be compact.As a result, providing a compact, high-output fuel cell becomespossible.

In the first and second embodiments, external manifolds 41, as well asthe first and second auxiliary manifolds 51, 52, were formed in theblock bodies 60, 90 that configure the end plates 32, 82; however, thepresent invention is not limited to this embodiment. For example, acollector plate may be configured from a block body, and externalmanifolds 41, as well as the first and second auxiliary manifolds 51,52, may be formed in this block body. Also, a dedicated block body onwhich fluid distribution devices 100, 101 are disposed may be used inaddition to the end plates and the collector plates.

Furthermore, in the first and second embodiments, the external manifolds41, as well as the first and second auxiliary manifolds 51, 52, wereformed by cutting the block body; however, the present invention is notlimited to this embodiment. For example, a similar structure may beformed using well-known techniques, such as casting or 3D printing. Inaddition, while the manufacturing of the fluid distribution devices 100,101 will become slightly more complicated, as compared to when using acutting operation, the external manifolds, as well as the first andsecond auxiliary manifolds, may be formed by connecting pipe members.

1. A fuel cell, comprising: a cell laminate body including asubstantially rectangular separator and a membrane electrode assemblylaminated together, the membrane electrode assembly equipped withsubstantially rectangular anode and cathode electrode layers located onopposite surfaces of a substantially rectangular electrolyte membraneand comprising an anode flow channel, a cathode flow channel, and acooling fluid channel inside; and an external manifold for anode gas andan external manifold for cathode gas disposed outside of the celllaminate body, and being configured to supply or discharge respectivefluids with respect to the cell laminate body, the cell laminate bodyincluding at least the anode flow channel and the cathode flow channel,the anode flow channel and the cathode flow channel being formed from aplurality of linear ribs, a length of the electrode layer along a flowchannel direction and a width of the electrode layer in a widthdirection perpendicular to the flow channel direction defining an aspectratio less than 1, the anode flow channel and the cathode flow channelhaving two or more flow channel openings disposed in each of first andsecond ends thereof, and the flow channel openings being laminated so asto form two or more fluid-supplying internal manifolds and two or morefluid-discharging internal manifolds for the anode gas and the cathodegas, the external manifold for the anode gas and the external manifoldfor the cathode gas including fluid-supplying external manifolds, whichconnect to the fluid-supplying internal manifolds via a supply-sidecommunicating portion, and fluid-discharging external manifolds, whichconnect to the fluid-discharging internal manifolds via a discharge-sidecommunicating portion, the fluid-supplying and fluid-dischargingexternal manifolds are positioned approximately parallel to each other,extending in the width direction of the cell laminate body, and thesupply-side communicating portion and the discharge-side communicatingportion comprise a first auxiliary manifold connected to the internalmanifold, and a second auxiliary manifold connected to the externalmanifold and comprises a center line that intersects a center line ofthe external manifold and a center line of the first auxiliary manifold,with respect to at least one fluid of the anode gas or the cathode gas.2. The fuel cell according to claim 1, wherein an inlet that opens atthe end of the fluid-supplying external manifold and an outlet thatopens at the end of the fluid-discharging external manifold arepositioned on one end side of the cell laminate body in the laminatelayer direction and open the same directions, with respect to at leastone fluid of the anode gas or the cathode gas.
 3. (canceled)
 4. The fuelcell according to claim 1, wherein a center line of each externalmanifold is offset to be inward of a center line of a respectiveinternal manifold.
 5. The fuel cell according to claim 1, wherein theexternal manifold for the cathode gas and the external manifold for theanode gas are disposed so as to overlap, and the external manifold forthe cathode gas is positioned to be closer to the cell laminate bodythan the external manifold for the anode gas.
 6. The fuel cell accordingto claim 1, wherein the external manifold for the cathode gas and theexternal manifold for the anode gas are disposed overlapping, and theexternal manifold for the cathode gas is positioned to be farther fromthe cell laminate body than the external manifold for the anode gas. 7.The fuel cell according to claim 1, wherein at least one of the internalmanifolds is disposed in a vertical direction and an external manifoldof the external manifolds connecting to the at least one of the internalmanifolds is disposed to be below the cell laminate body, at least in acathode.
 8. The fuel cell according to claim 1, wherein at least one ofthe internal manifold is disposed in a horizontal direction and anexternal manifolds of the external manifolds connecting to the at leastone of the internal manifolds is disposed to be below the internalmanifold, at least in a cathode.
 9. The fuel cell according to claim 1,wherein, the fluid-supplying external manifold, the first and secondauxiliary manifolds in the supply-side communicating portion, the firstand second auxiliary manifolds in the discharge-side communicatingportion, and the fluid-discharging external manifold are disposed insideof an end plate, with respect to two fluids of anode gas and cathodegas.
 10. The fuel cell according to claim 1, wherein a discharge-sidecross-sectional area of the external manifold for the cathode gas, whichuses cooling water and air, is larger than the cross-sectional area ofthe supply-side.
 11. (canceled)
 12. (canceled)
 13. A fluid distributiondevice of a fuel cell that distributes at least two fluids among ananode, a cathode, and a cooling fluid, comprising: a block body formingan end plate; first and second external manifolds for first and secondfluids, respectively, each of the first and second external manifoldsincluding a fluid-supplying external manifold and a fluid-dischargingexternal manifold, and being disposed in the block body, the block bodyincluding a surface on the side thereof configured have a cell laminatebody disposed thereon, the first external manifold for the first fluidflowing on a side closer to the surface configured have a cell laminatebody and the second external manifold for the second fluid flowing on aside farther from the surface are disposed so as to partially overlap,when viewed from the side of the surface of the block body, and thesecond external manifold for the second fluid includes an extensionportion that does not overlap with the first external manifold for thefirst fluid, when viewed from the side of the surface of the block body;a communicating portion for the first fluid is a first hole portioncommunicating only to the first external manifold for the first fluidfrom the surface; and a communicating portion for the second fluid is asecond hole portion that communicating only to the second externalmanifold for the second fluid in the extension portion from the surface.14. A vehicle comprising the fuel cell according to claim
 1. 15. Thefuel cell according to claim 2, wherein the external manifold for thecathode gas and the external manifold for the anode gas are disposed soas to overlap, and the external manifold for the cathode gas ispositioned to be closer to the cell laminate body than the externalmanifold for the anode gas.
 16. The fuel cell according to claim 4,wherein the external manifold for the cathode gas and the externalmanifold for the anode gas are disposed so as to overlap, and theexternal manifold for the cathode gas is positioned to be closer to thecell laminate body than the external manifold for the anode gas.
 17. Thefuel cell according to claim 2, wherein the external manifold for thecathode gas and the external manifold for the anode gas are disposedoverlapping, and the external manifold for the cathode gas is positionedto be farther from the cell laminate body than the external manifold forthe anode gas.
 18. The fuel cell according to claim 4, wherein theexternal manifold for the cathode gas and the external manifold for theanode gas are disposed overlapping, and the external manifold for thecathode gas is positioned to be farther from the cell laminate body thanthe external manifold for the anode gas.
 19. The fuel cell according toclaim 2, wherein at least one of the internal manifolds is disposed in avertical direction and an external manifold of the external manifoldsconnecting to the at least one of the internal manifolds is disposed tobe below the cell laminate body, at least in a cathode.
 20. The fuelcell according to claim 2, wherein at least one of the internal manifoldis disposed in a horizontal direction and an external manifolds of theexternal manifolds connecting to the at least one of the internalmanifolds is disposed to be below the internal manifold, at least in acathode.
 21. The fuel cell according to claim 2, wherein adischarge-side cross-sectional area of the external manifold in acathode, which uses cooling water and air, is larger than thecross-sectional area of the supply-side.
 22. The fuel cell according toclaim 4, wherein a discharge-side cross-sectional area of the externalmanifold in a cathode, which uses cooling water and air, is larger thanthe cross-sectional area of the supply-side.
 23. The fuel cell accordingto claim 5, wherein a discharge-side cross-sectional area of theexternal manifold in a cathode, which uses cooling water and air, islarger than the cross-sectional area of the supply-side.